// Copyright 2012 the V8 project authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#ifndef V8_COMPILATION_CACHE_H_
#define V8_COMPILATION_CACHE_H_

#include "src/allocation.h"
#include "src/objects/compilation-cache.h"

namespace v8 {
namespace internal {

    template <typename T>
    class Handle;

    class RootVisitor;

    // The compilation cache consists of several generational sub-caches which uses
    // this class as a base class. A sub-cache contains a compilation cache tables
    // for each generation of the sub-cache. Since the same source code string has
    // different compiled code for scripts and evals, we use separate sub-caches
    // for different compilation modes, to avoid retrieving the wrong result.
    class CompilationSubCache {
    public:
        CompilationSubCache(Isolate* isolate, int generations)
            : isolate_(isolate)
            , generations_(generations)
        {
            tables_ = NewArray<Object>(generations);
        }

        ~CompilationSubCache() { DeleteArray(tables_); }

        // Index for the first generation in the cache.
        static const int kFirstGeneration = 0;

        // Get the compilation cache tables for a specific generation.
        Handle<CompilationCacheTable> GetTable(int generation);

        // Accessors for first generation.
        Handle<CompilationCacheTable> GetFirstTable()
        {
            return GetTable(kFirstGeneration);
        }
        void SetFirstTable(Handle<CompilationCacheTable> value)
        {
            DCHECK_LT(kFirstGeneration, generations_);
            tables_[kFirstGeneration] = *value;
        }

        // Age the sub-cache by evicting the oldest generation and creating a new
        // young generation.
        void Age();

        // GC support.
        void Iterate(RootVisitor* v);

        // Clear this sub-cache evicting all its content.
        void Clear();

        // Remove given shared function info from sub-cache.
        void Remove(Handle<SharedFunctionInfo> function_info);

        // Number of generations in this sub-cache.
        inline int generations() { return generations_; }

    protected:
        Isolate* isolate() { return isolate_; }

    private:
        Isolate* isolate_;
        int generations_; // Number of generations.
        Object* tables_; // Compilation cache tables - one for each generation.

        DISALLOW_IMPLICIT_CONSTRUCTORS(CompilationSubCache);
    };

    // Sub-cache for scripts.
    class CompilationCacheScript : public CompilationSubCache {
    public:
        explicit CompilationCacheScript(Isolate* isolate);

        MaybeHandle<SharedFunctionInfo> Lookup(Handle<String> source,
            MaybeHandle<Object> name,
            int line_offset, int column_offset,
            ScriptOriginOptions resource_options,
            Handle<Context> native_context,
            LanguageMode language_mode);

        void Put(Handle<String> source, Handle<Context> context,
            LanguageMode language_mode,
            Handle<SharedFunctionInfo> function_info);

    private:
        bool HasOrigin(Handle<SharedFunctionInfo> function_info,
            MaybeHandle<Object> name, int line_offset, int column_offset,
            ScriptOriginOptions resource_options);

        DISALLOW_IMPLICIT_CONSTRUCTORS(CompilationCacheScript);
    };

    // Sub-cache for eval scripts. Two caches for eval are used. One for eval calls
    // in native contexts and one for eval calls in other contexts. The cache
    // considers the following pieces of information when checking for matching
    // entries:
    // 1. The source string.
    // 2. The shared function info of the calling function.
    // 3. Whether the source should be compiled as strict code or as sloppy code.
    //    Note: Currently there are clients of CompileEval that always compile
    //    sloppy code even if the calling function is a strict mode function.
    //    More specifically these are the CompileString, DebugEvaluate and
    //    DebugEvaluateGlobal runtime functions.
    // 4. The start position of the calling scope.
    class CompilationCacheEval : public CompilationSubCache {
    public:
        explicit CompilationCacheEval(Isolate* isolate)
            : CompilationSubCache(isolate, 1)
        {
        }

        InfoCellPair Lookup(Handle<String> source,
            Handle<SharedFunctionInfo> outer_info,
            Handle<Context> native_context,
            LanguageMode language_mode, int position);

        void Put(Handle<String> source, Handle<SharedFunctionInfo> outer_info,
            Handle<SharedFunctionInfo> function_info,
            Handle<Context> native_context, Handle<FeedbackCell> feedback_cell,
            int position);

    private:
        DISALLOW_IMPLICIT_CONSTRUCTORS(CompilationCacheEval);
    };

    // Sub-cache for regular expressions.
    class CompilationCacheRegExp : public CompilationSubCache {
    public:
        CompilationCacheRegExp(Isolate* isolate, int generations)
            : CompilationSubCache(isolate, generations)
        {
        }

        MaybeHandle<FixedArray> Lookup(Handle<String> source, JSRegExp::Flags flags);

        void Put(Handle<String> source,
            JSRegExp::Flags flags,
            Handle<FixedArray> data);

    private:
        DISALLOW_IMPLICIT_CONSTRUCTORS(CompilationCacheRegExp);
    };

    // The compilation cache keeps shared function infos for compiled
    // scripts and evals. The shared function infos are looked up using
    // the source string as the key. For regular expressions the
    // compilation data is cached.
    class V8_EXPORT_PRIVATE CompilationCache {
    public:
        // Finds the script shared function info for a source
        // string. Returns an empty handle if the cache doesn't contain a
        // script for the given source string with the right origin.
        MaybeHandle<SharedFunctionInfo> LookupScript(
            Handle<String> source, MaybeHandle<Object> name, int line_offset,
            int column_offset, ScriptOriginOptions resource_options,
            Handle<Context> native_context, LanguageMode language_mode);

        // Finds the shared function info for a source string for eval in a
        // given context.  Returns an empty handle if the cache doesn't
        // contain a script for the given source string.
        InfoCellPair LookupEval(Handle<String> source,
            Handle<SharedFunctionInfo> outer_info,
            Handle<Context> context, LanguageMode language_mode,
            int position);

        // Returns the regexp data associated with the given regexp if it
        // is in cache, otherwise an empty handle.
        MaybeHandle<FixedArray> LookupRegExp(
            Handle<String> source, JSRegExp::Flags flags);

        // Associate the (source, kind) pair to the shared function
        // info. This may overwrite an existing mapping.
        void PutScript(Handle<String> source, Handle<Context> native_context,
            LanguageMode language_mode,
            Handle<SharedFunctionInfo> function_info);

        // Associate the (source, context->closure()->shared(), kind) triple
        // with the shared function info. This may overwrite an existing mapping.
        void PutEval(Handle<String> source, Handle<SharedFunctionInfo> outer_info,
            Handle<Context> context,
            Handle<SharedFunctionInfo> function_info,
            Handle<FeedbackCell> feedback_cell, int position);

        // Associate the (source, flags) pair to the given regexp data.
        // This may overwrite an existing mapping.
        void PutRegExp(Handle<String> source,
            JSRegExp::Flags flags,
            Handle<FixedArray> data);

        // Clear the cache - also used to initialize the cache at startup.
        void Clear();

        // Remove given shared function info from all caches.
        void Remove(Handle<SharedFunctionInfo> function_info);

        // GC support.
        void Iterate(RootVisitor* v);

        // Notify the cache that a mark-sweep garbage collection is about to
        // take place. This is used to retire entries from the cache to
        // avoid keeping them alive too long without using them.
        void MarkCompactPrologue();

        // Enable/disable compilation cache. Used by debugger to disable compilation
        // cache during debugging to make sure new scripts are always compiled.
        void Enable();
        void Disable();

    private:
        explicit CompilationCache(Isolate* isolate);
        ~CompilationCache() = default;

        base::HashMap* EagerOptimizingSet();

        // The number of sub caches covering the different types to cache.
        static const int kSubCacheCount = 4;

        bool IsEnabled() const { return FLAG_compilation_cache && enabled_; }

        Isolate* isolate() const { return isolate_; }

        Isolate* isolate_;

        CompilationCacheScript script_;
        CompilationCacheEval eval_global_;
        CompilationCacheEval eval_contextual_;
        CompilationCacheRegExp reg_exp_;
        CompilationSubCache* subcaches_[kSubCacheCount];

        // Current enable state of the compilation cache.
        bool enabled_;

        friend class Isolate;

        DISALLOW_COPY_AND_ASSIGN(CompilationCache);
    };

} // namespace internal
} // namespace v8

#endif // V8_COMPILATION_CACHE_H_
